Which test is used to assess ACL integrity by applying an anterior force to the tibia with the knee flexed around 20–30 degrees?

Which test is used to assess ACL integrity by applying an anterior force to the tibia with the knee flexed around 20–30 degrees?

• A. Lachman test
• B. Anterior drawer test
• C. Pivot shift test
• D. Thessaly test

Answer: (A)

This examines ACL integrity by isolating the ACL with an anterior pull on the tibia when the knee is flexed about 20–30 degrees. The Lachman test is performed with the patient supine, one hand stabilizing the femur while the other gently translates the tibia forward. At this shallow flexion, the hamstrings are less able to mask ACL laxity, so the amount of anterior translation reflects the ACL’s integrity more directly than when the knee is bent to 90 degrees. In an ACL rupture, you’ll see increased anterior tibial movement compared with the opposite knee, often with a soft or absent end feel, indicating loss of ACL restraint. This makes it more sensitive than the anterior drawer test, which is done at 90 degrees and can be hindered by hamstring guarding or swelling. The other tests assess different aspects of knee stability: the pivot shift checks anterolateral rotary instability, and the Thessaly test evaluates meniscal pathology.

This examines ACL integrity by isolating the ACL with an anterior pull on the tibia when the knee is flexed about 20–30 degrees. The Lachman test is performed with the patient supine, one hand stabilizing the femur while the other gently translates the tibia forward. At this shallow flexion, the hamstrings are less able to mask ACL laxity, so the amount of anterior translation reflects the ACL’s integrity more directly than when the knee is bent to 90 degrees. In an ACL rupture, you’ll see increased anterior tibial movement compared with the opposite knee, often with a soft or absent end feel, indicating loss of ACL restraint. This makes it more sensitive than the anterior drawer test, which is done at 90 degrees and can be hindered by hamstring guarding or swelling. The other tests assess different aspects of knee stability: the pivot shift checks anterolateral rotary instability, and the Thessaly test evaluates meniscal pathology.